const fs = require('fs');

fs.readFile('./1.txt','utf8',(err,result1)=>{
    console.log(result1);
    fs.readFile('./2.txt','utf8',(err,result2)=>{
        console.log(result2);
        fs.readFile('./3.txt','utf8',(err,result3)=>{
            console.log(result3);
        })
    })
})